Co-assembly of nonspherical and heterogeneous nanoparticles in block copolymers

Nonspherical nanoparticles and heterogeneous can self-assemble into a microphase-separated block copolymer matrix creating complex structures, thanks to the colloidal orientational degrees of freedom, in addition to the inherent ordering of block copolymer melts. This can result in highly ordered materials where nanoparticles do not act as mere fillers but are decisive in the overall phase behaviour of the system. 2D and 3D mesoscopic simulations show the emergence of complex structures which can be radically different from the neat block copolymer.
Simulations are compared with SEM experimental images, finding several instances of emergent ordered phases at low and high concentrations, and a good match with semiconductive nanorods in asymmetric block copolymer. The crossover of block copolymer morphology and nanoparticle orientation is found to be determinant in the overall ordering of the system. Three dimensional simulations of anisotropic nanoparticles show the role of prolate spheroids seeding the global orientation of cylinder-forming block copolymer, as well as their ability to acquire orientational order within block copolymer melts.